1. Field of the Invention
The present invention relates to an improved roller-type linear guide.
2. Description of the Prior Art
A prior art roller-type linear guide is, for example, disclosed in Japanese Utility Model Laid-Open Publication NO. 57-42216. In this prior art linear guide, as shown in FIGS. 1 and 2, a truck 2 is straddlingly mounted on a track 1 having V-shaped grooves 1A and 1B formed in opposite sides thereof. The truck 2 has a plurality of rotating members 4 attached to opposite side walls 2A and 2B. The rotating members 4 include rollers 3 which roll in the V-shaped grooves 1A and 1B of the track 1. Furthermore, the setting angle of at least one pair of rotating shafts 5 of the rotating members 4 is 135.degree., and the setting angle of other rotating shafts is 45.degree.. As a result, when the truck 2 travels on the track 1, the rollers 3 of the rotating members 4 having the rotating shafts 5 whose setting angle is 135.degree. are in close contact with the upper surfaces of the V-shaped grooves 1A and 1B, and the rollers 3 of the rotating members 4 having the rotating shafts 5 whose setting angle is 45.degree. are in close contact with the lower surfaces of the V-shaped grooves 1A and 1B.
In the roller-type linear guide having the structure as mentioned above, there is a possibility of causing a looseness between the truck 2 and the track 1 supporting the former due to errors during manufacturing, such as a deviation in the inclination angle of the roller rotating shaft 5 and a center deflection of the roller 3, or attaching error of the rotating member 4, or non-uniform wear of the roller 3 caused by unbalanced load of a mounted member on the truck 2.
Furthermore, the prior art roller-type linear guide involves a problem in that no preload adjusting means effective in preventing the looseness has been taken into consideration.
Moreover, the prior art roller-type linear guide involves a problem in that the height of the truck should by all means be large so as to make the roller-type linear guide be disadvantageous for a compact design because where the height of the truck would be small it is difficult to ensure necessary width of inside space for inserting the rotating shaft of the rollers to be contacted to the lower surfaces of the V-shaped grooves 1A and 1B.